Petrographic and Sr-Nd-Pb-Li isotope characteristics of a
complex lamproite intrusion from the Saxo-Thuringian Zone: A
unique example of peralkaline mantle-derived melt
differentiation

J 2020

Petrographic and Sr-Nd-Pb-Li isotope characteristics of a complex lamproite intrusion from the Saxo-Thuringian Zone: A unique example of peralkaline mantle-derived melt differentiation

KRMÍČEK, Lukáš, Rolf L. ROMER, Jan CEMPÍREK, Petr GADAS, Simona KRMÍČKOVÁ et. al.

Základní údaje

Originální název

Petrographic and Sr-Nd-Pb-Li isotope characteristics of a complex lamproite intrusion from the Saxo-Thuringian Zone: A unique example of peralkaline mantle-derived melt differentiation

Autoři

KRMÍČEK, Lukáš (203 Česká republika), Rolf L. ROMER (756 Švýcarsko), Jan CEMPÍREK (203 Česká republika, domácí), Petr GADAS (203 Česká republika, domácí), Simona KRMÍČKOVÁ (203 Česká republika, garant, domácí) a Johannes GLODNY (276 Německo)

Vydání

Lithos, Amsterdam, Elsevier, 2020, 0024-4937

Další údaje

Jazyk

angličtina

Typ výsledku

Článek v odborném periodiku

Obor

10504 Mineralogy

Stát vydavatele

Nizozemské království

Utajení

není předmětem státního či obchodního tajemství

Odkazy

URL

Impakt faktor

Impact factor: 4.004

Kód RIV

RIV/00216224:14310/20:00117219

Organizační jednotka

Přírodovědecká fakulta

DOI

http://dx.doi.org/10.1016/j.lithos.2020.105735

UT WoS

000576647400005

Klíčová slova anglicky

Silica-rich lamproite; Baotite; Fractionation; Sr-Nd-Pb-Li isotopes; Orogenic mantle; Bohemian Massif

Štítky

rivok

Příznaky

Mezinárodní význam, Recenzováno

Změněno: 11. 3. 2021 09:53, Mgr. Marie Šípková, DiS.

Anotace

V originále

Variscan orogenic lamproites in the Bohemian Massif predominantly occur as 1 to 2 m wide and petrographically uniform dykes along the eastern borders of the Moldanubian and Saxo-Thuringian zones. Variscan orogenic lamproites were derived by preferential melting of subduction-related olivine-free metasomatic vein assemblages stabilised in the lithospheric mantle. These lamproitic melts may subsequently undergo extensive differentiation. In this study, we present the first combined petrographic and Sr-Nd-Pb-Li isotope characteristics of a complex lamproite exposed at ca 100 m long profile near Horni Rokytnice (Czech Republic) in the SaxoThuringian Zone. This lamproite is characterised by the primary mineral assemblage of K-amphibole Kfeldspar +/- aegirine and quartz that petrographically varies from relatively primitive (fine-grained, mafic) to more differentiated (medium- to coarse-grained, felsic) pegmatitic lamproite domains. These domains may represent the product of crystallisation of immiscible liquids that had separated from the mafic melt. The primitive lamproite zone is characterised by the typomorphic minerals - baotite, benitoite, and henrymeyerite. The more differentiated pegmatitic domains are free of aegirine and show replacement of primary red-luminescent (Fe3+-rich) K-feldspar by blue-luminescent (Fe-poor) K-feldspar. Residual fluids rich in Ca, Ti, and HFSE in combination with the decreasing peralkalinity of the lamproite system resulted in the local formation of secondary zircon, titanite and quartz at the expense of the primary Ti-Ba-Zr-K lamproitic mineral assemblages. Lamproites from the Moldanubian and Saxo-Thuringian zones fall on separate mixing trends in the Sr-87/Sr-86((t))- epsilon Nd-(t) diagram, which indicates that the mantle beneath these two zones had been metasomatised by different crustal material. The scatter in the peralkalinity index vs. delta(7) Li diagram indicates that the Li isotope composition is not controlled by mixing of two end members metasome and ambient depleted mantle alone, but may also be affected by late-stage magmatic and hydrothermal processes. The compositionally zoned Horni Rokytnice dyke is special as the petrographically different types show a variation of about 4 delta-units in delta(7) Li due to dyke-internal processes, such as fractionation, which increases delta(7) Li in late-stage lamproitic melts, and post-emplacement interaction with fluids that reduced delta(7) Li in samples that have lost Li. Post-emplacement alteration also led to the disturbance in the Pb isotope systematics of the differentiated orogenic lamproite as indicated by variable over-correction of in situ radiogenic Pb ingrowth.

Citovat

KRMÍČEK, Lukáš, Rolf L. ROMER, Jan CEMPÍREK, Petr GADAS, Simona KRMÍČKOVÁ a Johannes GLODNY. Petrographic and Sr-Nd-Pb-Li isotope characteristics of a complex lamproite intrusion from the Saxo-Thuringian Zone: A unique example of peralkaline mantle-derived melt differentiation. Lithos. Amsterdam: Elsevier, 2020, roč. 374, NOV 15 2020, s. 1-15. ISSN 0024-4937. Dostupné z: https://dx.doi.org/10.1016/j.lithos.2020.105735.

@article{1703476,
   author = {Krmíček, Lukáš and Romer, Rolf L. and Cempírek, Jan and Gadas, Petr and Krmíčková, Simona and Glodny, Johannes},
   article_location = {Amsterdam},
   article_number = {NOV 15 2020},
   doi = {http://dx.doi.org/10.1016/j.lithos.2020.105735},
   keywords = {Silica-rich lamproite; Baotite; Fractionation; Sr-Nd-Pb-Li isotopes; Orogenic mantle; Bohemian Massif},
   language = {eng},
   issn = {0024-4937},
   journal = {Lithos},
   note = {Doc. Krmíčka nedávat jako domácího tvůrce (nekmenový zaměstnanec).},
   title = {Petrographic and Sr-Nd-Pb-Li isotope characteristics of a complex lamproite intrusion from the Saxo-Thuringian Zone: A unique example of peralkaline mantle-derived melt differentiation},
   url = {https://doi.org/10.1016/j.lithos.2020.105735},
   volume = {374},
   year = {2020}
}

TY  - JOUR
ID  - 1703476
AU  - Krmíček, Lukáš - Romer, Rolf L. - Cempírek, Jan - Gadas, Petr - Krmíčková, Simona - Glodny, Johannes
PY  - 2020
TI  - Petrographic and Sr-Nd-Pb-Li isotope characteristics of a complex lamproite intrusion from the Saxo-Thuringian Zone: A unique example of peralkaline mantle-derived melt differentiation
JF  - Lithos
VL  - 374
IS  - NOV 15 2020
SP  - 1-15
EP  - 1-15
PB  - Elsevier
SN  - 00244937
N1  - Doc. Krmíčka nedávat jako domácího tvůrce (nekmenový zaměstnanec).
KW  - Silica-rich lamproite
KW  - Baotite
KW  - Fractionation
KW  - Sr-Nd-Pb-Li isotopes
KW  - Orogenic mantle
KW  - Bohemian Massif
UR  - https://doi.org/10.1016/j.lithos.2020.105735
L2  - https://doi.org/10.1016/j.lithos.2020.105735
N2  - Variscan orogenic lamproites in the Bohemian Massif predominantly occur as 1 to 2 m wide and petrographically uniform dykes along the eastern borders of the Moldanubian and Saxo-Thuringian zones. Variscan orogenic lamproites were derived by preferential melting of subduction-related olivine-free metasomatic vein assemblages stabilised in the lithospheric mantle. These lamproitic melts may subsequently undergo extensive differentiation. In this study, we present the first combined petrographic and Sr-Nd-Pb-Li isotope characteristics of a complex lamproite exposed at ca 100 m long profile near Horni Rokytnice (Czech Republic) in the SaxoThuringian Zone. This lamproite is characterised by the primary mineral assemblage of K-amphibole Kfeldspar +/- aegirine and quartz that petrographically varies from relatively primitive (fine-grained, mafic) to more differentiated (medium- to coarse-grained, felsic) pegmatitic lamproite domains. These domains may represent the product of crystallisation of immiscible liquids that had separated from the mafic melt. The primitive lamproite zone is characterised by the typomorphic minerals - baotite, benitoite, and henrymeyerite. The more differentiated pegmatitic domains are free of aegirine and show replacement of primary red-luminescent (Fe3+-rich) K-feldspar by blue-luminescent (Fe-poor) K-feldspar. Residual fluids rich in Ca, Ti, and HFSE in combination with the decreasing peralkalinity of the lamproite system resulted in the local formation of secondary zircon, titanite and quartz at the expense of the primary Ti-Ba-Zr-K lamproitic mineral assemblages. Lamproites from the Moldanubian and Saxo-Thuringian zones fall on separate mixing trends in the Sr-87/Sr-86((t))- epsilon Nd-(t) diagram, which indicates that the mantle beneath these two zones had been metasomatised by different crustal material. The scatter in the peralkalinity index vs. delta(7) Li diagram indicates that the Li isotope composition is not controlled by mixing of two end members metasome and ambient depleted mantle alone, but may also be affected by late-stage magmatic and hydrothermal processes. The compositionally zoned Horni Rokytnice dyke is special as the petrographically different types show a variation of about 4 delta-units in delta(7) Li due to dyke-internal processes, such as fractionation, which increases delta(7) Li in late-stage lamproitic melts, and post-emplacement interaction with fluids that reduced delta(7) Li in samples that have lost Li. Post-emplacement alteration also led to the disturbance in the Pb isotope systematics of the differentiated orogenic lamproite as indicated by variable over-correction of in situ radiogenic Pb ingrowth.
ER  -

KRMÍČEK, Lukáš, Rolf L. ROMER, Jan CEMPÍREK, Petr GADAS, Simona KRMÍČKOVÁ a Johannes GLODNY. Petrographic and Sr-Nd-Pb-Li isotope characteristics of a complex lamproite intrusion from the Saxo-Thuringian Zone: A unique example of peralkaline mantle-derived melt differentiation. \textit{Lithos}. Amsterdam: Elsevier, 2020, roč.~374, NOV 15 2020, s.~1-15. ISSN~0024-4937. Dostupné z: https://dx.doi.org/10.1016/j.lithos.2020.105735.

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